It is already known from the document EP 0 246 958 such a connecting device operating by a symmetric double cutting and comprising two substantially parallel flanges:                connecting opposite edges of said elements by providing together the mechanical strength of said connection,        arranging between them a groove in which a pyrotechnic fuse with an oblong section with flat flanks and rounded ends is housed, said flat flanks being substantially parallel and respectively arranged opposite said flanges, and        each provided with a rupture area, said rupture areas of both flanges being on the same side of said elements.        
In the connecting device of this prior document, the rupture areas present a section being tapered in the plan perpendicular to the flat flanks of the fuse, and thus a smaller resistance to the abrupt expansion of said fuse after the activation thereof. These rupture areas are identical and arranged on a coplanar way. i.e. at the same level with respect to the pyrotechnic fuse, and more precisely in the vicinity of the top of the rounded end being located on the side of said rupture areas. Both flanges are in turn parallel to the flat flanks of the fuse and of a same thickness.
Upon the activation of the fuse, the latter abruptly expands and strikes both flanges, which leads to the rupture of said flanges at the level of their rupture areas, and thus the separation, and then the removal of the two elements initially connected by the device, this removal occurring in a direction being parallel to the flat flanks of the fuse.
Due to the perfect symmetry of the above mentioned connecting device, the shock waves appearing upon the fuse strike, propagating within the flanges and being transmitted to the adjacent elements so as to induce vibrations therein, are at least partially neutralized. Indeed, the rupture areas are sectioned simultaneously and on the same way due to the effect of the fuse expansion, which generates in both flanges shock waves not only in phase agreement, but also of the same nature and level, thus absolutely identical. It results therefrom that, upon the superposition of such waves at the level of the elements being adjacent to the flanges, some of the harmonics cancel each other out. The resulting vibration suffered by said elements, especially the one an element being integral with a spatial machine would suffer, is thus significantly reduced.
Such connecting device with a symmetric double cutting thus allows the separation of two elements by means of a pyrotechnic fuse, while limiting the vibrations that were generated by the impact of the fuse and that said elements are subjected to.
However, although such device is perfectly convenient for an axial removal of the elements, i.e. parallel to the flat flanks of the fuse, a major drawback is met when the matter is to remove said elements along one direction being at least partially transverse to said flat flanks, as it is the case in most of the satellite protecting covers, into several parts where a thrust is exerted in the transverse direction to said flat flanks so as to make the disengagement of each of the parts of said covers easier.
Indeed, at the level of each of the flanges, the breaking surface of each of the two separated parts of the flange, generated by the rupture being subsequent to the fuse activation, is irregular. Upon then, when said two elements are removed from each other at least in part laterally, said two parts separated from the flange are at a risk to be mutually caught, at the level of the irregularities their respective breaking surfaces are provided with. It thus results therefrom a significantly downgraded relative removal of both elements.
Moreover, in the case, for example, of the separation of an invariable (lower) element and an ejecting (higher) element forming the cover of a spatial machine, said machine is propelled along the direction being parallel to the flat flanks of the fuse and in a direction from the invariable element to the ejecting element. The thrust force generated by the propulsion of said machine then tends to make said elements closer after their separation, said two elements being then able to strike each other and thus to be mutually caught.